9-(1-propynyl)-9-hydroxyquinone represented by the formula: ##STR3## and 2,5-bis(2,4-dimethylphenyl) hydroquinone were previously known as acetylene-type compounds capable of forming a complex with an alcohol in an aqueous alcoholic solution such as aqueous ethanol solution, [with reference to a report entitled "Specific compounds capable of recognizing molecules" in the Abstract of lectures at the Joint Meeting in The Autumn Session of The 38th Annual Meeting of The Chemical Society of Japan (including the combined forum), Announcement Meeting of Kagaku-kankei Rengo-kyokai and Autumn Session of Chubu Kagaku-kankei Kyokai-shibu-rengo, published by The Chemical Society of Japan, a corporate juridical body (1978) and Chemical Letters, pp. 1699-1702 (1983), published by The Chemical Society of Japan.]